Spray drying atomizer wheel

Abstract

Milk or similar liquids are spray dried using a rotary atomizer wheel whereby such a temperature is imparted to the liquid that a violent release of gas and vapor from the liquid takes place in the atomizer wheel, which gas and vapor are removed before the atomization of the liquid. By these means a powder having at high bulk density and a low content of occluded air is obtained. A special atomizer wheel, having two sets of ejection apertures and two intercommunicating supply compartments makes it possible to eject released gas and vapor through one set of apertures and liquid through the other set, whereby reintroduction in the liquid of the released air is prevented. Also an atomizer wheel of this type is provided wherein the two supply compartments are steam-swept.

What we claim is: 
     
       1. An atomizer comprising: (a) an atomizer wheel having means defining two annular compartments, the wheel further having in its periphery a first set of ejection apertures connected to one of the compartments and a second set of ejection apertures connected to the second compartment, said first set of ejection apertures being constructed in such a way that they are substantially filled with liquid during the operation of the atomizer, the wheel having means for providing fluid communication between the two compartments,   (b) a shaft on which the atomizer wheel is secured,   (c) means for rotating said wheel,   (d) a stationary casing having means defining two concentric ducts annularly around the shaft which both terminate in the first compartment,   (e) an inlet pipe for liquid communicating with one of the concentric ducts, and   (f) an inlet pipe for steam communicating with the other of the concentric ducts.   
     
     
       2. An atomizer as claimed in claim 1, wherein the gap between the stationary casing of the atomizer and the atomizer wheel communicates freely with the atmosphere outside the drying chamber and, a filter interposed between the gap and the outside atmosphere. 
     
     
       3. An atomizer as claimed in claim 1, wherein a feed pipe is disposed between the atomizer wheel and the stationary casing of the atomizer for supplying air under a pressure which is sufficient to impede an inwardly directed airstream in the gap between the wheel and the casing. 
     
     
       4. An atomizer as claimed in claim 1, characterized in that on the side of the atomizer wheel facing toward the stationary casing of the atomizer a plurality of vanes are mounted to impede an inwardly directed airstream in the gap between the wheel and the casing.